package com.demo.jzoffer2;

import com.demo.domain.TreeNode;
import org.junit.Test;

/**
 * 还未提交
 * @author gy
 * @date 2023/01/12
 */
public class Test0113_01 {

    /**
     * 给定一个二叉树, 找到该树中两个指定节点的最近公共祖先。
     *
     * 百度百科中最近公共祖先的定义为：“对于有根树 T 的两个结点 p、q，最近公共祖先表示为一个结点 x，
     * 满足 x 是 p、q 的祖先且 x 的深度尽可能大（一个节点也可以是它自己的祖先）。”
     *
     * 输入: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1
     * 输出: 3
     * 解释: 节点 5 和节点 1 的最近公共祖先是节点 3。
     *
     * 输入: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4
     * 输出: 5
     * 解释: 节点 5 和节点 4 的最近公共祖先是节点 5。因为根据定义最近公共祖先节点可以为节点本身。
     *
     * 例如，给定如下二叉树:  root = [3,5,1,6,2,0,8,null,null,7,4]
     * @param root
     * @param p
     * @param q
     * @return
     */
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if (root == null || root == p || root == q){
            return root;
        }
        TreeNode left = lowestCommonAncestor(root.left, p, q);
        TreeNode right = lowestCommonAncestor(root.right, p, q);
        if (left == null && right == null){
            return null;
        }
        if (left == null){
            return right;
        }
        if (right == null){
            return left;
        }
        return root; // left != null && right != null
    }


    @Test
    public void m1() {
        TreeNode root = new TreeNode(3);
        TreeNode a = new TreeNode(5);
        TreeNode b = new TreeNode(1);
        TreeNode c = new TreeNode(6);
        TreeNode d = new TreeNode(2);
        TreeNode e = new TreeNode(0);
        TreeNode f = new TreeNode(8);
        TreeNode g = new TreeNode(7);
        TreeNode h = new TreeNode(4);

        root.left = a;
        root.right = b;
        root.left.left = c;
        root.left.right = d;
        root.right.left = e;
        root.right.right = f;

        root.left.right.left = g;
        root.left.right.right = h;

        System.out.println(root);
        System.out.println("===");

    }

    @Test
    public void m2(){

    }

}
